Method for preventing the formation of recesses in borophosphosilicate glass

Abstract

A method for preventing the formation of recesses in the surface of a borophosphosilicate glass layer comprising the step of first forming a borophosphosilicate glass layer over a substrate, then forming a silicon nitride film having a thickness of about 300Å to 1000Å over the borophosphosilicate glass layer. Next, contact windows are formed, followed by cleaning with an RCA solution. The silicon nitride film provides a protective function preventing the formation of recesses on the borophosphosilicate glass surface. Consequently, no short-circuiting metal bridges caused by metal in the recesses after the deposition of metallic conducting wires are formed.

What is claimed is: 
     
       1. A method for preventing the formation of recesses in borophosphosilicate glass used for the planarization of a substrate, comprising the steps of: forming a borophosphosilicate glass layer over a substrate;   forming an insulating layer on the borophosphosilicate glass (BPSG) layer to prevent formation of recesses on the surface of the BPSG layer during a cleaning process;   removing portions of the insulating layer and the borophosphosilicate glass layer to form a plurality of contact windows; and   after forming the contact windows, cleaning exposed surfaces of the remaining insulating layer on the remaining BPSG layer with a cleaning solution.   
     
     
       2. The method of claim 1, wherein the step of forming the insulating layer includes depositing a thin film of silicon nitride. 
     
     
       3. The method of claim 2, wherein the silicon nitride film has a thickness of 300Å to 1000Å. 
     
     
       4. The method of claim 2, wherein the step of forming the silicon nitride film includes using a low pressure chemical vapor deposition method. 
     
     
       5. The method of claim 1, wherein the step of removing portions of the insulating layer and the borophosphosilicate glass layer includes using photolithographic and etching processes. 
     
     
       6. The method of claim 4, wherein the step of removing portions of the insulating layer and the borophosphosilicate glass layer includes the following substeps: forming a photoresist layer over the insulating layer;   patterning the photoresist layer to form a mask, then removing portions of the insulating layer and the borophosphosilicate glass layer to form a plurality of contact windows; and   removing the photoresist layer.   
     
     
       7. A method for preventing the formation of recesses in borophosphosilicate glass, comprising the steps of: providing a substrate;   forming a borophosphosilicate glass layer over the substrate;   forming an insulating layer on the borophosphosilicate glass (BPSG) layer to prevent formation of recesses on the surface of the BPSG layer during a cleaning process;   forming a photoresist layer over the insulating layer;   patterning the photoresist layer to form a mask, and then removing portions of the insulating layer and the borophosphosilicate glass layer to form a plurality of contact windows;   removing the photoresist layer; and   cleaning the exposed surfaces of the remaining insulating layer on the remaining BPSG layer with a cleaning solution.   
     
     
       8. The method of claim 7, wherein the step of forming the insulating layer includes depositing a thin film of silicon nitride. 
     
     
       9. The method of claim 8, wherein the step of forming the silicon nitride film includes using a low pressure chemical vapor deposition method. 
     
     
       10. The method of claim 8, wherein the silicon nitride film has a thickness of 300Å to 1000Å.